<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>圆角图形</title>
    <style>
        .item{
            margin-bottom: 10px;
            width: 180px;
            height: 180px;
            border: 1px solid #cccccc;
            border-radius:50%;
        }
        .bagua{
            height: 90px;
            background-color: red;
            border-bottom-width: 90px;
            border-bottom-color: green;
            border-style: solid;
            position: relative;
        }

        .bagua::after,.bagua::before{
            position: absolute;
            content: "";
            top: 50%;
            width: 20px;
            height: 20px;
            border-width: 35px;
            background-color: white;
            border-radius: 50%;
            border-style: solid;
        }

        .bagua::after{
            border-color: red;
            left:0;
        }

        .bagua::before{
            border-color: green;
            right:0;
        }
    </style>
</head>
<body>
    <h1>八卦图</h1>
    <div class="item bagua"></div>
</body>
</html>